In vitro maturation (IVM) of immature oocytes obtained from patients with polycystic ovarian syndrome (PCOS) is considered as a novel strategy in order to reduce clinical side effects and cost of in vitro fertilization (IVF) technique. The aim of this study was to evaluate the effects of PCOS whole and steroid-depleted serums on in vitro oocyte maturation indices. Patients with PCOS were selected according to the Rotterdam criteria. Cumulus-oocyte complexes and blood serums were collected and pooled. Cumulus cells and immature oocytes were treated with 10% whole or steroid-depleted serums. Stearoyl-CoA desaturase-1 (SCD1) and cyclooxygenase-2 (COX2) expression levels in cumulus cells were evaluated by quantitative PCR. Fatty acid composition of cumulus cells was analyzed using gas-liquid chromatography. Polar body observation was considered as the oocyte maturation index. Oleate (1.28-fold, p = .006), SCD1 expression (450-fold, p = .001), and COX2 expression (35-fold, p = .02) in cumulus cell, as well as oocyte maturation (p < .001) and in vitro embryo development (p < .05) were significantly higher in treatment with steroid-depleted serum compared to that of whole serum. Steroid depletion of PCOS serum improved its capacity to increase success rate of oocyte maturation, intra-cytoplasmic sperm injection and early embryo development.